1. Field of the Invention
This invention relates to a network device which has a server function.
2. Description of the Related Art
In recent years, the networking using IP (Internet Protocol) is expected to grow in use, and the IP is adopted by many network devices. Although the IP was constructed by considering the use over the Internet as a premise, it is now widely applied to private networks, and many people benefit from the effects of the IP.
In the IP, network devices communicate with each other using IP addresses. As shown in FIG. 1, a network device #1 which originates communication acquires the IP address of a destination network device #2 using a certain mechanism, and realizes the communication by transmitting a packet from its own IP address to the IP address of the destination and receiving a packet therefrom.
The IP which is most widely used at present is IPv4 (Internet Protocol version 4). According to this IP, about 4,200 million IP addresses are prepared. Namely, it can be said that 4,200 million network devices can communicate with each other. However, the population in the world already exceeds 6 billion people, and this means that one person cannot have a network device according to IPv4.
In fact, one person usually uses two or more IP network devices. For example, one person has a PC (personal computer) for office use and has also another PC for home use. Moreover, besides the PCs, the person may have a cellular phone capable of performing IP communication, a digital camera capable of performing IP communication, and home electronics, such as a videocassette recorder and a home server. In such a situation, the number of 4,200 million IPv4 addresses is too small.
To solve the problem, a new IP called IPv6 (Internet Protocol version 6) has been proposed. While the IPv4 address was 32 bits in length and the number of IP addresses was 4,200 million, the IPv6 address has an extended length to 128 bits. Thereby, the number of IP addresses which can be used according to the IPv6 becomes an astronomical numerical value, and a substantially infinite number of network devices can communicate with each other.
According to the IPv6, IP addresses can be assigned for miscellaneous network devices which were not able to use IP. According to the IPv4, one IP address was assigned to one network device, while according to the IPv6, assigning two or more IP addresses to one network device is taken into consideration.
When management of the IPv6 address is carried out, the IP address is divided into two parts: a prefix part and a suffix part. Specifically, as shown in FIG. 2, the higher-rank 64 bits of the 128-bit IP address are called a prefix, and the lower-rank 64 bits thereof are called a suffix.
In IPv6 environment, it is supposed that IP addresses generally are automatically set up except for the special cases. In the automatic setting of IP addresses, a prefix and a suffix are determined separately and a new 128-bit IP address is created by combining them.
In the case of IPv6 address called a link local address, a prefix is a fixed value and it is predetermined according to the specification of IPv6. Namely, the fixed value of the prefix is “fe80:0000:0000:0000::/64”. In many cases in which a global address is determined, the global address is determined according to the information indicated in a packet called RA (router advertisement) which is transmitted over a network. In the RA, a prefix which is valid within the network is contained. Thus, the prefix to be allocated for each network device is obtained from the information indicated in the RA.
The suffix is individually determined by each network device. In many cases, each network device uses its own MAC (media access control) address as the base and sets up an IP address for the network device. The MAC address usually is managed according to the 48-bit numbering system called EUI (extended unique identifier)-48. It is guaranteed that, if a MAC address follows the EUI-48, it is unique among those following the EUI-48. For this reason, the duplication of a MAC address may not take place among NICs (network interface cards) in the world.
And EUI-64 is proposed as the high-order standard of EUI-48. The numbering system according to EUI-48 is mapped to EUI-64, and converting the numerical value of EUI-48 into the numerical value of EUI-64 is possible.
A 64-bit numerical value of EUI-64 is generated from a MAC address by using the above-mentioned conversion, so that the suffix is obtained.
As a result of the above procedure, the prefix and the suffix are obtained, and a 128-bit numerical value can be generated by combining them. The generated IPv6 address is set up for the network device concerned.
Any publication of the prior art technology that is particularly relevant to this invention cannot be discovered at the time of filing of the application. Therefore, information on prior art documents is not disclosed.
A network device inherently provides a certain network service according to a request of a user, but the IP address of the network device may be an IPv4 address which is arbitrarily defined by the administrator, or an IPv6 address which is automatically set up based on the MAC address as mentioned above. There is a problem that it is difficult to discover the network service from another network device of the side which requests the network service.
Moreover, the network service and the IP address conventionally have no direct association, and the setting of filtering, routing, IPsec (security architecture for Internet Protocol), etc. must be individually perform for every IP address. Such operation is complicated.